A magnetic random access memory (MRAM) device is a memory including a magnetic tunnel junction (MTJ), and includes two magnetic layers (an upper magnetic layer and a lower magnetic layer), and an insulating layer provided between the two magnetic layers. For example, in a case of an MRAM disclosed in Japanese Patent Laid-Open Publication No. 2012-64901, a laminate protruding from an upper magnetic layer is formed above an insulating layer through etching, a part of the upper magnetic layer is included in the laminate, and the surface of the laminate and the surface of the upper magnetic layer on which the laminate is formed are covered with an insulating film. The insulating film is, for example, a SiN film as disclosed in, for example, “Improvement of Thermal Stability of Magnetoresistive Random Access Memory Device with SiN Protective Film Deposited by High-Density Plasma Chemical Vapor Deposition,” Katsumi SUEMITSU et al., Japanese Journal of Applied Physics, Vol. 47, No. 4, 2008, pp. 2714-2718. The SiN film is generally formed by plasma of a processing gas containing SiH4 and NH3.
When a plasma-enhanced chemical vapor deposition (plasma CVD) is used for forming an insulating film, two magnetic layers and the insulating layer are affected by heat of plasma. Study results on such an effect of the heat have been reported on, for example, “Annealing effects on CoFeB—MgO magnetic tunnel junctions with perpendicular anisotropy,” H. Meng et al., Journal of Applied Physics, 110, 033904 (2011). Further, an upper magnetic layer and a lower magnetic layer of an MRAM have a property (a perpendicular magnetic anisotropy) of being easily magnetized in a direction perpendicular to a substrate (in a direction parallel to a laminate). Study results on a property of a perpendicular magnetic anisotropy in an edge of a magnetic layer such as an upper magnetic layer have been reported on, for example, “Reversal mechanisms in perpendicularly magnetized nanostructures,” Justin M. Shaw et al., Physical Review B 78, 024414 (2008).